X射线衍射-X射线荧光光谱-电子探针等分析测试技术在玄武岩矿物鉴定中的应用  

Application of X-ray Diffraction,X-ray Fluorescence Spectrometry and Electron Microprobe in the Identification of Basalt

作　　者：许乃岑[1,2] 沈加林[1,2] 张静[1,2] 

机构地区：[1]中国地质调查局南京地质调查中心,江苏南京210016 [2]国土资源部华东矿产资源监督检测中心,江苏南京210016

出　　处：《岩矿测试》2015年第1期75-81,共7页Rock and Mineral Analysis

基　　金：国土资源部公益性行业科研专项"火成岩岩石矿物鉴定检测技术方法研究"项目(201011029-2)

摘　　要：玄武岩的鉴定通常采用显微镜镜下判定,鉴定结果容易受到鉴定人员的专业水平和主观因素、切片方位的影响,光性特征有差异,再者颗粒细小的矿物还受到光学显微镜本身放大倍数的限制也很难准确鉴定。当前的鉴定方法已由传统的显微镜向现代分析仪器(X射线衍射仪、电子探针、X射线荧光光谱仪等)综合研究方向发展。本文采用X射线粉晶衍射(XRD)和显微镜镜下观测相结合的方法,对安徽女山玄武岩(未经蚀变)和团山玄武岩(经过蚀变)进行鉴定,并采用X射线荧光光谱仪(XRF)和电子探针对鉴定结果进行验证。结果表明:女山玄武岩用显微镜鉴定主要由基质(74%,斜长石44%+辉石30%)和斑晶(13%)组成,还含有少量金属矿物(8%)及较大颗粒石英捕掳晶(5%);其中,基质部分的斜长石经XRD分析可进一步确定为拉长石,辉石主要为普通辉石(单斜辉石),少量金属矿物为钛铁矿。团山玄武岩用显微镜鉴定主要由基质(75%,斜长石50%+辉石25%)和斑晶(9%)组成,还含有少量绿泥石充填的杏仁体;其中,基质部分的斜长石经XRD分析可进一步确定为微斜长石,蚀变矿物为蒙脱石而非薄片鉴定中的绿泥石。综合XRD和相关技术鉴定结果可确定,女山玄武岩主要矿物为拉长石、辉石、钛铁矿;团山玄武岩主要矿物为微斜长石、辉石、蒙脱石。研究显示,单独的显微鉴定技术在含蚀变矿物的玄武岩鉴定中会产生较大偏差,而结合XRD等多种分析测定技术可以快速鉴定出矿物种类,尤其对颗粒较小的矿物鉴定的准确度更高。Basalt identification is usually performed by microscope,so the appraisal results are easily influenced by personal professional level and subjective factors.Influenced by slice orientation,there are differences between the optical characteristics.Moreover,tiny mineral is also limited by optical microscope magnification itself.It is difficult to accurately identify basalt.Basalt rock mineral identification has been developed from traditional microscope identification to a variety of instrument determination,such as X-ray Diffraction（XRD）,Electron Probe and X-ray Fluorescence Spectrometer（XRF）,etc.XRD and the method of observation under microscope lens were used to identify two kinds of basalt,nvshan basalt（without alteration） and tuanshan basalt（with alteration）.XRF and Electron Probe are used to validate the results of the appraisal.The Microscope identification analysis results show that the nvshan basalt（without alteration） is mainly composed of 74% matrix（inclusive of44% plagioclase and 30% pyroxene） and 13% phenocryst,and also contains a small amount of 8% metal minerals and larger particles quartz crystal capture（5%）.Microscopic identification of the matrix of plagioclase,by XRD can be further identified as labradorite,pyroxene mainly for ordinary pyroxene（monoclinic pyroxene）,a small amount of metal minerals can be determined as ilmenite.Tuanshan basalt（after alteration） microscope identification is mainly composed of 75% matrix（inclusive of 50% plagioclase and 25% pyroxene） and 9%phenocryst,and also contains a small amount of chlorite filling the amygdale.Among them,the microscopic identification matrix of plagioclase can be further identified as microcline by XRD analysis,the alteration minerals montmorillonite instead of thin section identification of chlorite.The comprehensive appraisal result of XRD and related technologies show that nvshan basalt can be composed of minerals such as feldspar,pyroxene,ilmenite and the main minerals of Tuanshan basalt can be desig

关 键 词：玄武岩 矿物鉴定 岩石薄片显微镜鉴定 X射线粉晶衍射法 X射线荧光光谱法 电子探针 

分 类 号：P588.145[天文地球—岩石学] P575.5[天文地球—地质学]